Condenser MEMS microphones typically have a diaphragm that forms a capacitor with an underlying backplate. Receipt of an audible signal causes the diaphragm to vibrate to form a variable capacitance signal representing the audible signal. It is this variable capacitance signal that can be amplified, recorded, or otherwise transmitted to another electronic device.
The area of the diaphragm has a direct relation to the total capacitance of the microphone. If too small, it may produce a signal that can be relatively easily corrupted by noise. In addition, a small diaphragm also may produce a signal that is too small to be measured. Conversely, if too large (but having the same thickness as a smaller diaphragm), the diaphragm may bow and thus, produce corrupted signals. Microphones having bowed diaphragms also may have less favorable sensitivity and signal-to-noise ratios.